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LibJS: Consolidate sources of system time zone to one location in Date

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This is a normative change in the ECMA-262 spec. See:
43fd5f2

For the most part, these AOs are hoisted from Temporal.

Note that despite being a normative change, the expectation is that
this change does not result in any behavior differences.
This commit is contained in:
Timothy Flynn 2022-10-14 09:23:43 -04:00 • committed by Linus Groh
parent e952dca026
commit 019211bcb4
3 changed files with 293 additions and 18 deletions
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272
Userland/Libraries/LibJS/Runtime/Date.cpp
View file

@ -11,11 +11,16 @@
#include <LibJS/Runtime/AbstractOperations.h>
#include <LibJS/Runtime/Date.h>
#include <LibJS/Runtime/GlobalObject.h>
#include <LibJS/Runtime/Temporal/ISO8601.h>
#include <LibTimeZone/TimeZone.h>
#include <time.h>
namespace JS {
static Crypto::SignedBigInteger const s_one_billion_bigint { 1'000'000'000 };
static Crypto::SignedBigInteger const s_one_million_bigint { 1'000'000 };
static Crypto::SignedBigInteger const s_one_thousand_bigint { 1'000 };
Date* Date::create(Realm& realm, double date_value)
{
return realm.heap().allocate<Date>(realm, date_value, *realm.intrinsics().date_prototype());
@ -265,6 +270,7 @@ u8 week_day(double t)
}
// 21.4.1.7 LocalTZA ( t, isUTC ), https://tc39.es/ecma262/#sec-local-time-zone-adjustment
// FIXME: Remove this when ECMA-402 is synced with https://github.com/tc39/ecma262/commit/43fd5f25357333d8340bfb486b8f0738e6d0d0cb.
double local_tza(double time, [[maybe_unused]] bool is_utc, Optional<StringView> time_zone_override)
{
// The time_zone_override parameter is non-standard, but allows callers to override the system
@ -285,21 +291,160 @@ double local_tza(double time, [[maybe_unused]] bool is_utc, Optional<StringView>
return maybe_offset.has_value() ? static_cast<double>(maybe_offset->seconds) * 1000 : 0;
}
// 21.4.1.8 LocalTime ( t ), https://tc39.es/ecma262/#sec-localtime
// 21.4.1.7 GetUTCEpochNanoseconds ( year, month, day, hour, minute, second, millisecond, microsecond, nanosecond ), https://tc39.es/ecma262/#sec-getutcepochnanoseconds
Crypto::SignedBigInteger get_utc_epoch_nanoseconds(i32 year, u8 month, u8 day, u8 hour, u8 minute, u8 second, u16 millisecond, u16 microsecond, u16 nanosecond)
{
// 1. Let date be MakeDay(𝔽(year), 𝔽(month - 1), 𝔽(day)).
auto date = make_day(year, month - 1, day);
// 2. Let time be MakeTime(𝔽(hour), 𝔽(minute), 𝔽(second), 𝔽(millisecond)).
auto time = make_time(hour, minute, second, millisecond);
// 3. Let ms be MakeDate(date, time).
auto ms = make_date(date, time);
// 4. Assert: ms is an integral Number.
VERIFY(ms == trunc(ms));
// 5. Return ℤ(ℝ(ms) × 10^6 + microsecond × 10^3 + nanosecond).
auto result = Crypto::SignedBigInteger { ms }.multiplied_by(s_one_million_bigint);
result = result.plus(Crypto::SignedBigInteger { static_cast<i32>(microsecond) }.multiplied_by(s_one_thousand_bigint));
result = result.plus(Crypto::SignedBigInteger { static_cast<i32>(nanosecond) });
return result;
}
static i64 clip_bigint_to_sane_time(Crypto::SignedBigInteger const& value)
{
static Crypto::SignedBigInteger const min_bigint { NumericLimits<i64>::min() };
static Crypto::SignedBigInteger const max_bigint { NumericLimits<i64>::max() };
// The provided epoch (nano)seconds value is potentially out of range for AK::Time and subsequently
// get_time_zone_offset(). We can safely assume that the TZDB has no useful information that far
// into the past and future anyway, so clamp it to the i64 range.
if (value < min_bigint)
return NumericLimits<i64>::min();
if (value > max_bigint)
return NumericLimits<i64>::max();
// FIXME: Can we do this without string conversion?
return value.to_base(10).to_int<i64>().value();
}
// 21.4.1.8 GetNamedTimeZoneEpochNanoseconds ( timeZoneIdentifier, year, month, day, hour, minute, second, millisecond, microsecond, nanosecond ), https://tc39.es/ecma262/#sec-getnamedtimezoneepochnanoseconds
Vector<Crypto::SignedBigInteger> get_named_time_zone_epoch_nanoseconds(StringView time_zone_identifier, i32 year, u8 month, u8 day, u8 hour, u8 minute, u8 second, u16 millisecond, u16 microsecond, u16 nanosecond)
{
auto local_nanoseconds = get_utc_epoch_nanoseconds(year, month, day, hour, minute, second, millisecond, microsecond, nanosecond);
auto local_time = Time::from_nanoseconds(clip_bigint_to_sane_time(local_nanoseconds));
// FIXME: LibTimeZone does not behave exactly as the spec expects. It does not consider repeated or skipped time points.
auto offset = TimeZone::get_time_zone_offset(time_zone_identifier, local_time);
// Can only fail if the time zone identifier is invalid, which cannot be the case here.
VERIFY(offset.has_value());
return { local_nanoseconds.plus(Crypto::SignedBigInteger { offset->seconds }.multiplied_by(s_one_billion_bigint)) };
}
// 21.4.1.9 GetNamedTimeZoneOffsetNanoseconds ( timeZoneIdentifier, epochNanoseconds ), https://tc39.es/ecma262/#sec-getnamedtimezoneoffsetnanoseconds
i64 get_named_time_zone_offset_nanoseconds(StringView time_zone_identifier, Crypto::SignedBigInteger const& epoch_nanoseconds)
{
// Only called with validated time zone identifier as argument.
auto time_zone = TimeZone::time_zone_from_string(time_zone_identifier);
VERIFY(time_zone.has_value());
// Since Time::from_seconds() and Time::from_nanoseconds() both take an i64, converting to
// seconds first gives us a greater range. The TZDB doesn't have sub-second offsets.
auto seconds = epoch_nanoseconds.divided_by(s_one_billion_bigint).quotient;
auto time = Time::from_seconds(clip_bigint_to_sane_time(seconds));
auto offset = TimeZone::get_time_zone_offset(*time_zone, time);
VERIFY(offset.has_value());
return offset->seconds * 1'000'000'000;
}
// 21.4.1.10 DefaultTimeZone ( ), https://tc39.es/ecma262/#sec-defaulttimezone
StringView default_time_zone()
{
return TimeZone::current_time_zone();
}
// 21.4.1.11 LocalTime ( t ), https://tc39.es/ecma262/#sec-localtime
double local_time(double time)
{
// 1. Return t + LocalTZA(t, true).
return time + local_tza(time, true);
// 1. Let localTimeZone be DefaultTimeZone().
auto local_time_zone = default_time_zone();
double offset_nanoseconds { 0 };
// 2. If IsTimeZoneOffsetString(localTimeZone) is true, then
if (is_time_zone_offset_string(local_time_zone)) {
// a. Let offsetNs be ParseTimeZoneOffsetString(localTimeZone).
offset_nanoseconds = parse_time_zone_offset_string(local_time_zone);
}
// 3. Else,
else {
// a. Let offsetNs be GetNamedTimeZoneOffsetNanoseconds(localTimeZone, ℤ(ℝ(t) × 10^6)).
auto time_bigint = Crypto::SignedBigInteger { time }.multiplied_by(s_one_million_bigint);
offset_nanoseconds = get_named_time_zone_offset_nanoseconds(local_time_zone, time_bigint);
}
// 4. Let offsetMs be truncate(offsetNs / 10^6).
auto offset_milliseconds = trunc(offset_nanoseconds / 1e6);
// 5. Return t + 𝔽(offsetMs).
return time + offset_milliseconds;
}
// 21.4.1.9 UTC ( t ), https://tc39.es/ecma262/#sec-utc-t
// 21.4.1.12 UTC ( t ), https://tc39.es/ecma262/#sec-utc-t
double utc_time(double time)
{
// 1. Return t - LocalTZA(t, false).
return time - local_tza(time, false);
// 1. Let localTimeZone be DefaultTimeZone().
auto local_time_zone = default_time_zone();
double offset_nanoseconds { 0 };
// 2. If IsTimeZoneOffsetString(localTimeZone) is true, then
if (is_time_zone_offset_string(local_time_zone)) {
// a. Let offsetNs be ParseTimeZoneOffsetString(localTimeZone).
offset_nanoseconds = parse_time_zone_offset_string(local_time_zone);
}
// 3. Else,
else {
// a. Let possibleInstants be GetNamedTimeZoneEpochNanoseconds(localTimeZone, ℝ(YearFromTime(t)), ℝ(MonthFromTime(t)) + 1, ℝ(DateFromTime(t)), ℝ(HourFromTime(t)), ℝ(MinFromTime(t)), ℝ(SecFromTime(t)), ℝ(msFromTime(t)), 0, 0).
auto possible_instants = get_named_time_zone_epoch_nanoseconds(local_time_zone, year_from_time(time), month_from_time(time) + 1, date_from_time(time), hour_from_time(time), min_from_time(time), sec_from_time(time), ms_from_time(time), 0, 0);
// b. NOTE: The following steps ensure that when t represents local time repeating multiple times at a negative time zone transition (e.g. when the daylight saving time ends or the time zone offset is decreased due to a time zone rule change) or skipped local time at a positive time zone transition (e.g. when the daylight saving time starts or the time zone offset is increased due to a time zone rule change), t is interpreted using the time zone offset before the transition.
Crypto::SignedBigInteger disambiguated_instant;
// c. If possibleInstants is not empty, then
if (!possible_instants.is_empty()) {
// i. Let disambiguatedInstant be possibleInstants[0].
disambiguated_instant = move(possible_instants.first());
}
// d. Else,
else {
// i. NOTE: t represents a local time skipped at a positive time zone transition (e.g. due to daylight saving time starting or a time zone rule change increasing the UTC offset).
// ii. Let possibleInstantsBefore be GetNamedTimeZoneEpochNanoseconds(localTimeZone, ℝ(YearFromTime(tBefore)), ℝ(MonthFromTime(tBefore)) + 1, ℝ(DateFromTime(tBefore)), ℝ(HourFromTime(tBefore)), ℝ(MinFromTime(tBefore)), ℝ(SecFromTime(tBefore)), ℝ(msFromTime(tBefore)), 0, 0), where tBefore is the largest integral Number < t for which possibleInstantsBefore is not empty (i.e., tBefore represents the last local time before the transition).
// iii. Let disambiguatedInstant be the last element of possibleInstantsBefore.
// FIXME: This branch currently cannot be reached with our implementation, because LibTimeZone does not handle skipped time points.
// When GetNamedTimeZoneEpochNanoseconds is updated to use a LibTimeZone API which does handle them, implement these steps.
VERIFY_NOT_REACHED();
}
// e. Let offsetNs be GetNamedTimeZoneOffsetNanoseconds(localTimeZone, disambiguatedInstant).
offset_nanoseconds = get_named_time_zone_offset_nanoseconds(local_time_zone, disambiguated_instant);
}
// 4. Let offsetMs be truncate(offsetNs / 10^6).
auto offset_milliseconds = trunc(offset_nanoseconds / 1e6);
// 5. Return t - 𝔽(offsetMs).
return time - offset_milliseconds;
}
// 21.4.1.11 MakeTime ( hour, min, sec, ms ), https://tc39.es/ecma262/#sec-maketime
// 21.4.1.14 MakeTime ( hour, min, sec, ms ), https://tc39.es/ecma262/#sec-maketime
double make_time(double hour, double min, double sec, double ms)
{
// 1. If hour is not finite or min is not finite or sec is not finite or ms is not finite, return NaN.
@ -334,7 +479,7 @@ double time_within_day(double time)
return modulo(time, ms_per_day);
}
// 21.4.1.12 MakeDay ( year, month, date ), https://tc39.es/ecma262/#sec-makeday
// 21.4.1.15 MakeDay ( year, month, date ), https://tc39.es/ecma262/#sec-makeday
double make_day(double year, double month, double date)
{
// 1. If year is not finite or month is not finite or date is not finite, return NaN.
@ -367,7 +512,7 @@ double make_day(double year, double month, double date)
return day(static_cast<double>(t)) + dt - 1;
}
// 21.4.1.13 MakeDate ( day, time ), https://tc39.es/ecma262/#sec-makedate
// 21.4.1.16 MakeDate ( day, time ), https://tc39.es/ecma262/#sec-makedate
double make_date(double day, double time)
{
// 1. If day is not finite or time is not finite, return NaN.
@ -385,7 +530,7 @@ double make_date(double day, double time)
return tv;
}
// 21.4.1.14 TimeClip ( time ), https://tc39.es/ecma262/#sec-timeclip
// 21.4.1.17 TimeClip ( time ), https://tc39.es/ecma262/#sec-timeclip
double time_clip(double time)
{
// 1. If time is not finite, return NaN.
@ -400,4 +545,111 @@ double time_clip(double time)
return to_integer_or_infinity(time);
}
// 21.4.1.19.1 IsTimeZoneOffsetString ( offsetString ), https://tc39.es/ecma262/#sec-istimezoneoffsetstring
bool is_time_zone_offset_string(StringView offset_string)
{
// 1. Let parseResult be ParseText(StringToCodePoints(offsetString), UTCOffset).
auto parse_result = Temporal::parse_iso8601(Temporal::Production::TimeZoneNumericUTCOffset, offset_string);
// 2. If parseResult is a List of errors, return false.
// 3. Return true.
return parse_result.has_value();
}
// 21.4.1.19.2 ParseTimeZoneOffsetString ( offsetString ), https://tc39.es/ecma262/#sec-parsetimezoneoffsetstring
double parse_time_zone_offset_string(StringView offset_string)
{
// 1. Let parseResult be ParseText(StringToCodePoints(offsetString), UTCOffset).
auto parse_result = Temporal::parse_iso8601(Temporal::Production::TimeZoneNumericUTCOffset, offset_string);
// 2. Assert: parseResult is not a List of errors.
VERIFY(parse_result.has_value());
// 3. Assert: parseResult contains a TemporalSign Parse Node.
VERIFY(parse_result->time_zone_utc_offset_sign.has_value());
// 4. Let parsedSign be the source text matched by the TemporalSign Parse Node contained within parseResult.
auto parsed_sign = *parse_result->time_zone_utc_offset_sign;
i8 sign { 0 };
// 5. If parsedSign is the single code point U+002D (HYPHEN-MINUS) or U+2212 (MINUS SIGN), then
if (parsed_sign.is_one_of("-"sv, "\xE2\x88\x92"sv)) {
// a. Let sign be -1.
sign = -1;
}
// 6. Else,
else {
// a. Let sign be 1.
sign = 1;
}
// 7. NOTE: Applications of StringToNumber below do not lose precision, since each of the parsed values is guaranteed to be a sufficiently short string of decimal digits.
// 8. Assert: parseResult contains an Hour Parse Node.
VERIFY(parse_result->time_zone_utc_offset_hour.has_value());
// 9. Let parsedHours be the source text matched by the Hour Parse Node contained within parseResult.
auto parsed_hours = *parse_result->time_zone_utc_offset_hour;
// 10. Let hours be ℝ(StringToNumber(CodePointsToString(parsedHours))).
auto hours = string_to_number(parsed_hours)->as_double();
double minutes { 0 };
double seconds { 0 };
double nanoseconds { 0 };
// 11. If parseResult does not contain a MinuteSecond Parse Node, then
if (!parse_result->time_zone_utc_offset_minute.has_value()) {
// a. Let minutes be 0.
minutes = 0;
}
// 12. Else,
else {
// a. Let parsedMinutes be the source text matched by the first MinuteSecond Parse Node contained within parseResult.
auto parsed_minutes = *parse_result->time_zone_utc_offset_minute;
// b. Let minutes be ℝ(StringToNumber(CodePointsToString(parsedMinutes))).
minutes = string_to_number(parsed_minutes)->as_double();
}
// 13. If parseResult does not contain two MinuteSecond Parse Nodes, then
if (!parse_result->time_zone_utc_offset_second.has_value()) {
// a. Let seconds be 0.
seconds = 0;
}
// 14. Else,
else {
// a. Let parsedSeconds be the source text matched by the second secondSecond Parse Node contained within parseResult.
auto parsed_seconds = *parse_result->time_zone_utc_offset_second;
// b. Let seconds be ℝ(StringToNumber(CodePointsToString(parsedSeconds))).
seconds = string_to_number(parsed_seconds)->as_double();
}
// 15. If parseResult does not contain a TemporalDecimalFraction Parse Node, then
if (!parse_result->time_zone_utc_offset_fraction.has_value()) {
// a. Let nanoseconds be 0.
nanoseconds = 0;
}
// 16. Else,
else {
// a. Let parsedFraction be the source text matched by the TemporalDecimalFraction Parse Node contained within parseResult.
auto parsed_fraction = *parse_result->time_zone_utc_offset_fraction;
// b. Let fraction be the string-concatenation of CodePointsToString(parsedFraction) and "000000000".
auto fraction = String::formatted("{}000000000", parsed_fraction);
// c. Let nanosecondsString be the substring of fraction from 1 to 10.
auto nanoseconds_string = fraction.substring_view(1, 9);
// d. Let nanoseconds be ℝ(StringToNumber(nanosecondsString)).
nanoseconds = string_to_number(nanoseconds_string)->as_double();
}
// 17. Return sign × (((hours × 60 + minutes) × 60 + seconds) × 10^9 + nanoseconds).
// NOTE: Using scientific notation (1e9) ensures the result of this expression is a double,
// which is important - otherwise it's all integers and the result overflows!
return sign * (((hours * 60 + minutes) * 60 + seconds) * 1e9 + nanoseconds);
}
}

6
Userland/Libraries/LibJS/Runtime/Date.h
View file

@ -63,6 +63,10 @@ u8 sec_from_time(double);
u16 ms_from_time(double);
u8 week_day(double);
double local_tza(double time, bool is_utc, Optional<StringView> time_zone_override = {});
Crypto::SignedBigInteger get_utc_epoch_nanoseconds(i32 year, u8 month, u8 day, u8 hour, u8 minute, u8 second, u16 millisecond, u16 microsecond, u16 nanosecond);
Vector<Crypto::SignedBigInteger> get_named_time_zone_epoch_nanoseconds(StringView time_zone_identifier, i32 year, u8 month, u8 day, u8 hour, u8 minute, u8 second, u16 millisecond, u16 microsecond, u16 nanosecond);
i64 get_named_time_zone_offset_nanoseconds(StringView time_zone_identifier, Crypto::SignedBigInteger const& epoch_nanoseconds);
StringView default_time_zone();
double local_time(double time);
double utc_time(double time);
double day(double);
@ -71,5 +75,7 @@ double make_time(double hour, double min, double sec, double ms);
double make_day(double year, double month, double date);
double make_date(double day, double time);
double time_clip(double time);
bool is_time_zone_offset_string(StringView offset_string);
double parse_time_zone_offset_string(StringView offset_string);
}

33
Userland/Libraries/LibJS/Runtime/DatePrototype.cpp
View file

@ -1117,18 +1117,35 @@ String date_string(double time)
// 21.4.4.41.3 TimeZoneString ( tv ), https://tc39.es/ecma262/#sec-timezoneestring
String time_zone_string(double time)
{
// 1. Let offset be LocalTZA(tv, true).
auto offset = local_tza(time, true);
// 1. Let localTimeZone be DefaultTimeZone().
auto local_time_zone = default_time_zone();
double offset_nanoseconds { 0 };
// 2. If IsTimeZoneOffsetString(localTimeZone) is true, then
if (is_time_zone_offset_string(local_time_zone)) {
// a. Let offsetNs be ParseTimeZoneOffsetString(localTimeZone).
offset_nanoseconds = parse_time_zone_offset_string(local_time_zone);
}
// 3. Else,
else {
// a. Let offsetNs be GetNamedTimeZoneOffsetNanoseconds(localTimeZone, ℤ(ℝ(tv) × 10^6)).
auto time_bigint = Crypto::SignedBigInteger { time }.multiplied_by(Crypto::UnsignedBigInteger { 1'000'000 });
offset_nanoseconds = get_named_time_zone_offset_nanoseconds(local_time_zone, time_bigint);
}
// 4. Let offset be 𝔽(truncate(offsetNs / 106)).
auto offset = trunc(offset_nanoseconds / 1e6);
StringView offset_sign;
// 2. If offset is +0𝔽 or offset > +0𝔽, then
// 5. If offset is +0𝔽 or offset > +0𝔽, then
if (offset >= 0) {
// a. Let offsetSign be "+".
offset_sign = "+"sv;
// b. Let absOffset be offset.
}
// 3. Else,
// 6. Else,
else {
// a. Let offsetSign be "-".
offset_sign = "-"sv;
@ -1136,13 +1153,13 @@ String time_zone_string(double time)
offset *= -1;
}
// 4. Let offsetMin be ToZeroPaddedDecimalString(ℝ(MinFromTime(absOffset)), 2).
// 7. Let offsetMin be ToZeroPaddedDecimalString(ℝ(MinFromTime(absOffset)), 2).
auto offset_min = min_from_time(offset);
// 5. Let offsetHour be ToZeroPaddedDecimalString(ℝ(HourFromTime(absOffset)), 2).
// 8. Let offsetHour be ToZeroPaddedDecimalString(ℝ(HourFromTime(absOffset)), 2).
auto offset_hour = hour_from_time(offset);
// 6. Let tzName be an implementation-defined string that is either the empty String or the string-concatenation of the code unit 0x0020 (SPACE), the code unit 0x0028 (LEFT PARENTHESIS), an implementation-defined timezone name, and the code unit 0x0029 (RIGHT PARENTHESIS).
// 9. Let tzName be an implementation-defined string that is either the empty String or the string-concatenation of the code unit 0x0020 (SPACE), the code unit 0x0028 (LEFT PARENTHESIS), an implementation-defined timezone name, and the code unit 0x0029 (RIGHT PARENTHESIS).
auto tz_name = TimeZone::current_time_zone();
// Most implementations seem to prefer the long-form display name of the time zone. Not super important, but we may as well match that behavior.
@ -1151,7 +1168,7 @@ String time_zone_string(double time)
tz_name = long_name.release_value();
}
// 7. Return the string-concatenation of offsetSign, offsetHour, offsetMin, and tzName.
// 10. Return the string-concatenation of offsetSign, offsetHour, offsetMin, and tzName.
return String::formatted("{}{:02}{:02} ({})", offset_sign, offset_hour, offset_min, tz_name);
}